The pond volume calculator calculates your pond's volume in gallons and liters based on shape and dimensions. Also shows fish stocking capacity and chemical treatment guidance.
Planning Your Garden Pond
Knowing your pond's volume is fundamental for fish stocking, chemical treatments, pump sizing, and filtration planning. Most pond problems — algae blooms, fish deaths, water quality issues — trace back to overstocking or under-filtering a pond whose volume was never accurately calculated.
Pump and filter sizing
A pond pump should cycle the entire pond volume once per hour at minimum — twice per hour for koi ponds. A 1,500-gallon koi pond needs a pump rated 1,500-3,000 GPH (gallons per hour). Filter capacity should match pump output. Under-filtering is the most common cause of green water and fish health problems in backyard ponds.
Frequently Asked Questions
How do I calculate pond volume?
For a rectangle: Length × Width × Depth. For a circle: π × radius² × depth. For an oval: 0.785 × Length × Width × Depth. Multiply cubic feet by 7.481 to get gallons (US). This calculator handles all three shapes automatically.
How many fish can I put in my pond?
The classic rule is 1 inch of fish per 10 gallons of water. So a 1,000-gallon pond can hold 100 inches of fish (e.g., 10 fish averaging 10 inches each). With proper filtration and aeration, experienced pond keepers use 1 inch per 5 gallons.
How much dechlorinator do I need?
Most dechlorinators treat 1,000 gallons per capful (varies by brand). Knowing your exact pond volume lets you dose accurately. Under-dosing leaves chloramines that stress fish; over-dosing wastes product.
Is this calculator free?
Yes, completely free with no signup required.